This invention relates generally to mixers and more specifically to a conduction mixer and method of conduction mixing for rapidly heating or cooling materials during a mixing cycle.
The concept of material heating and cooling devices that also mix materials is known in the art. In one type of a particulate material heating and cooling device, which is shown in the Forberg U.S. Pat. No. 4,791,735, a gas is forced down along the sides of the container and into direct contact with the materials as the materials are mixed. The gas is then allowed to discharge through a vent in the top of the mixer. This type of mixer requires capping the hopper to prevent material from being blown out of the hopper. In addition, the time required for mixing and heating or cooling a particulate material is considerable.
The present invention presents a new type of material heating and cooling device that can simultaneously mix material without having a heating or cooling gas contact the material being mixed. The present invention isolates a heat transfer fluid from the material and directs the heat transfer fluid through a shaft and a set of mixing members of the system to conductively transfer heat between the heat transfer fluid and the material to be mixed without contamination of the mixed material. In addition, the conductive heat transfer between the heat transfer fluid and the material allows one to more quickly raise or lower the temperature of the mixing material since one can provide large surface contact areas between the material to be mixed and the surfaces of the mixing members.
Forberg U.S. Pat. No. 4,791,735 shows a mixer wherein a gas is forced directly into the particulate material as the particulate material are being mixed.
A method of mixing and a conduction mixer having a hopper for receiving a material to be mixed, a mixing member mounted in the hopper and movable in the hopper to mix the material in the hopper and a source of heat transfer fluid connected to the mixing member to direct the heat transfer fluid through either or both a heat transfer jacket or the mixing member to enable the mixing member to simultaneously mix and conductively transfer heat between the heat transfer fluid and the material.